Geometry node group inputs and outputs get a new property that controls
the attribute name used for that field input/output when assigning the
node group to a modifier for the first time. If the default name is assigned
to an input, the default "Use attribute name" is true .
In order to properly detect when a node group is first assigned,
the modifier now clears its properties when clearing the node group.
Ref T96707
Differential Revision: https://developer.blender.org/D14761